In recent years, a multiplicity of methods have been reported as methods of specifying the position of portable telephone terminals (hereinbelow referred to as “terminals”). A number of standardization organizations are standardizing positioning methods and positioning sequences for specifying the positions of terminals.
The Third General Partnership Project (hereinbelow abbreviated as “3GPP”), which is one of the organizations implementing standardization and that has established the standards for W-CDMA, is proceeding with the standardization of positioning methods and positioning sequences. Three positioning methods have already been established in TS25.305, which is the document giving the 3GPP standards: a positioning method that uses signals from GPS satellites; a positioning method that uses signals from base stations; and a positioning method that uses information of the sectors in which terminals are located.
Of the three positioning methods described above, the positioning method that uses signals from base stations uses the time differences of the arrival times of pilot signals from two base stations that have been measured at the terminal to specify the position of the terminal.
However, because base stations do not operate in synchronization in a W-CDMA network, the transmission timing of pilot signals does not coincide. In order to specify the position of a terminal with high accuracy, the time difference in the arrival times of pilot signals that has been measured at the terminal must be corrected by a timing differential of the transmission of the pilot signals from the base stations. This timing differential is referred to as the “Relative Time Difference” and is hereinbelow abbreviated as “RTD.”
Two types of methods for measuring RTD are prescribed in TS 25.305, which is the document for the 3GPP standards. The following explanation regards each of these measuring methods.
FIG. 1 is a figure for explaining one of the methods for measuring RTD that have been established by the 3GPP.
The system shown in FIG. 1 is made up from RNC 101 and base stations 102 and 103.
RNC 101 is a device for controlling base stations 102 and 103.
Base stations 102 and 103 are devices that use radio to communicate with terminals (not shown) and operate under the control of RNC 101.
FIG. 2 shows the configuration of RNC 101. FIG. 2 shows only that portion of the configuration that is needed for the explanation.
RNC 101 shown in FIG. 2 is made up from: control unit 301, message processor 302, message transceiver 303, and memory 304.
Control unit 301 serves the role of controlling the RTD measurement sequence and the calculation of the RTD based on the measurement results.
Message processor 302 generates messages in accordance with requests from control unit 301, and issues requests to message transceiver 303 to transmit messages that have been generated. In addition, message processor 302 further checks the content of messages that have been reported from message transceiver 303 and reports the type and content of these messages to control unit 301.
Message transceiver 303 transmits messages in accordance with requests from message processor 302 and reports the reception of messages to message process 302.
Memory 304 stores the RTD.
FIG. 3 shows the configuration of base stations 102 and 103. FIG. 3 shows only those portions of the configuration that are necessary for the explanation.
Base stations 102 and 103 shown in FIG. 3 are each made up from: control unit 401, message processor 402, message transceiver 403, radio signal transceiver 404, transmission timing measurement unit 405, and GPS signal receiver 406.
Control unit 401 issues requests for the transmission of transmission times to transmission timing measurement unit 405 in accordance with the content of messages that are reported from message processor 402. Control unit 401 further issues requests to message processor 402 to generate messages for reporting the results of measurement in transmission timing measurement unit 405.
Message processor 402 generates messages in accordance with requests from control unit 401 and issues requests to message transceiver 403 for the transmission of messages that have been generated. Message processor 402 further checks the content of messages that have been reported from message transceiver 403 and reports the type and content of these messages to control unit 401.
Message transceiver 403 transmits messages in accordance with requests from message processor 402 and reports the reception of messages to message processor 402.
Radio signal transceiver 404 has the capability to transmit radio signals to terminals and to receive radio signals from terminals.
Transmission timing measurement unit 405 measures the transmission times of pilot signals that are transmitted from radio signal transceiver 404 in accordance with requests from control unit 401, and reports the results of measurement to control unit 401. Transmission timing measurement unit 405 further uses GPS times that are reported from GPS signal receiver 406 in the measurement of transmission timings.
GPS signal receiver 406 receives signals from GPS satellites and reports the GPS times that are contained in the received signals to transmission timing measurement unit 405.
FIG. 4 is a view for explaining the sequence when measuring the RTD.
When measuring the RTD, control unit 301 of RNC 101 issues a request to message processor 302 to transmit messages to base stations 102 and 103 requesting the measurement of the transmission times of pilot signals. Upon receiving the request, message processor 302 generates measurement request messages and transmits the measurement request messages to base stations 102 and 103 by way of message transceiver 303 (Step 501a and Step 501b).
Upon receiving the measurement request messages from RNC 101, message transceivers 403 of base stations 102 and 103 report the reception of the messages and the content of the received messages to respective message processors 402. Each message processor 402 refers to the content of the reported message, recognizes the reception of the measurement request message from RNC 101, and notifies control unit 401 of the reception of a measurement request message from RNC 101.
Having received the report of the measurement request message, control unit 401 checks the content of the measurement request. In this case, control unit 401 verifies that the measurement of the transmission timings of pilot signals has been requested and issues a request to transmission timing measurement unit 405 for the measurement of the transmission timings.
Upon receiving the request for measurement, transmission timing measurement unit 405 measures the transmission timings of pilot signals that have been transmitted from radio signal transceiver 405 (Step 502a and Step 502b.) The transmission timings are represented by the GPS time that is reported from GPS signal receiver 406. After measurement has been completed, transmission timing measurement unit 405 reports the measurement result to control unit 401.
Control unit 401, having been notified of the result of the measurement of the transmission timings, issues a request to message processor 402 for the transmission of a message to report the measurement results to RNC 101. Message processor 402, having received the request, generates a measurement result report message and issues a request to message transceiver 403 to transmit the generated message. Message transceiver 403, having received the request for message transmission, transmits the measurement result report message to RNC 101 (Step 503a and Step 503b).
Message transceiver 303 of RNC 101 reports the reception of the message and the content of the received message to message processor 302. Message processor 302, having received this notification, checks the content of the message and reports the reception of the measurement result report message from base station 102 or base station 103 to control unit 301. At this time, message processor 302 simultaneously reports the measurement results to control unit 301.
Control unit 301 calculates the difference in the transmission timings that have been reported from base stations 102 and 103, computes the RTD, and stores the RTD in memory 304 (Step 504).
FIG. 5 is a view for explaining another RTD measurement method that has been established by 3GPP. This method uses measurement nodes referred to as Location Measurement Units (hereinbelow abbreviated as “LMU”).
The system shown in FIG. 5 is made up from: RNC 601, base stations 602 and 603, and LMU 604.
RNC 601 is a device for realizing control of base stations 602 and 603. RNC 601 is of identical configuration to RNC 101 and explanation of the configuration is therefore here omitted.
Base stations 602 and 603 are devices that use radio lines to realize communication with terminals (not shown) and operate under the control of RNC 601. In addition, base stations 602 and 603 are of the same configuration as base stations 102 and 103, and explanation of their configuration is therefore here omitted. In addition, RNC 601 recognizes the geographical location of base stations 602 and 603.
LMU 604 is a device for measuring the reception timings of pilot signals that are transmitted from base stations 602 and 603. RNC 601 further recognizes the geographical location of LMU 604.
FIG. 6 is a view showing the configuration of LMU 604.
LMU 604 shown in FIG. 6 is made up from: control unit 701, message processor 702, message transceiver 703, radio signal transceiver 704, and reception timing measurement unit 705.
Control unit 701 issues requests to reception timing measurement unit 705 for the measurement of the reception timings of pilot signals in accordance with the content of messages that are reported from message processor 702. Control unit 701 further issues requests to message processor 702 for the generation of messages to report the results of measurement in reception timing measurement unit 705.
Message processor 702 generates messages in accordance with requests from control unit 701 and issues requests to message transceiver 703 for the transmission of generated messages. Message processor 702 further checks the content of messages that are reported from message transceiver 703 and reports the type and content of the messages to control unit 701.
Message transceiver 703 transmits messages in accordance with requests from message processor 702 and reports the reception of messages to message processor 702.
Radio signal transceiver 704 has the capability to transmit radio signals to base stations 602 and 603 and to receive radio signals from base stations 602 and 603.
FIG. 7 is a view for explaining the sequence for the RTD measurement that uses LMU 604.
When measuring the RTD, control unit 301 of RNC 601 issues a request to message processor 302 to transmit a message to LMU 604 requesting the measurement of the time difference of the reception times of pilot signals received from base stations 602 and 603. Upon receiving the request, message processor 302 generates a measurement request message and transmits the measurement request message to LMU 604 by way of message transceiver 303 (Step 801). At this time, message processor 302 simultaneously reports to LMU 604 information by which LMU 604 specifies base stations 602 and 603 that are to be the objects of measurement.
Upon receiving the measurement request message from RNC 601, message receiver 703 of LMU 604 reports the reception of the message and the content of the received message to message processor 702. Message processor 702 refers to the content of the reported message to verify that a measurement request message has been received from RNC 601, and reports the reception of the measurement request message from RNC 601 to control unit 701.
Control unit 701, having been notified of the measurement request message, checks the content of the measurement request. In this case, control unit 701 recognizes that measurement of the time difference between the reception times of pilot signals has been requested and issues a request to reception timing measurement unit 705 for the measurement of the reception times of the pilot signals received from base stations 602 and 603.
Reception timing measurement unit 705, having received the request for measurement, measures the reception times of the pilot signals received at radio signal transceiver 704 for each of base stations 602 and 603 (Step 802).
Control unit 701, having been notified of the results of measuring the reception times, takes the difference between the reception times of the pilot signals from each of base stations 602 and 603, and calculates the time difference. Control unit 701 then issues a request to message processor 702 for the transmission of a message to report the calculation results to RNC 601. Message processor 703, having received this request, generates a measurement result report message and issues a request to message transceiver 703 for the transmission of the generated message. Message transceiver 703, having received the request for transmission of the message, transmits the measurement result report message to RNC 601 (Step 803).
Message transceiver 303 of RNC 601 reports the reception of the message and the content of the received message to message processor 302. Message processor 302, having received the report, checks the content of the message and reports the reception of the measurement result report message from LMU 604 to control unit 301. At this time, message processor 302 simultaneously reports the measurement results to control unit 301.
In control unit 301, the distance between LMU 604 and base station 602 and the distance between LMU 604 and base station 603 are calculated based on the geographical locations of base stations 602 and 603 and the geographical location of LMU 604, and further, the difference in propagation times is calculated based on the calculated distances. Control unit 301 then compares the time difference of the reception times that have been reported from LMU 604 with the difference in propagation times to calculate the RTD and stores the calculation results in memory 304 (Step 804).
In addition, in a mobile communication network such as a W-CDMA network, a technique known as “soft hand-over” is used to support conversation or data communication during movement. Soft hand-over is a method of simultaneously using a plurality of base stations to communicate whereby, even when communication becomes impossible with one base station, communication can be continued with the remaining base stations.
FIG. 8 is a figure for explaining soft hand-over.
The system shown in FIG. 8 is made up from RNC 901, base stations 902 and 903, and terminal 904.
RNC 901 is a device for controlling base stations 902 and 903 and terminal 904. RNC 901 is of the same configuration as RNC 101, and explanation of configuration is therefore here omitted.
Base stations 902 and 903 are devices that use radio lines to communicate with terminal 904 and that operate under the control of RNC 901. Base stations 902 and 903 are of the same configuration as base stations 102 and 103, and explanation of the configuration is therefore here omitted.
Terminal 904 is a device used for conversation or data communication between users and communicates by establishing a connection with RNC 901 by way of base station 902 or base station 903.
FIG. 9 shows the configuration of terminal 904. FIG. 9 shows only those portions that are necessary for the explanation.
Terminal 904 shown in FIG. 9 is made up from: control unit 1001, message processor 1002, message transceiver 1003, radio signal transceiver 1004, signal measurement unit 1005, and radio link control unit 1006.
Control unit 1001 issues requests to signal measurement unit 1005 to measure the reception quality of pilot signals. Control unit 1001 further issues requests to message processor 1002 to generate messages for reporting the measurement results of signal measurement unit 1005.
Message processor 1002 generates messages in accordance with requests from control unit 1001 and issues requests to message transceiver 1003 to transmit generated messages. Message processor 1002 further checks the content of messages that have been reported from message transceiver 1003 and reports the type and content of these messages to control unit 1001.
Message transceiver 1003 transmits messages in accordance with requests from message processor 1002 and reports the reception of messages to message processor 1002.
Radio signal transceiver 1004 has the capability for transmitting radio signals to base stations that have been designated from radio link control unit 1006 and for receiving radio signals from base stations that have been designated from radio link control unit 1006. Radio signal transceiver 1004 further has the capability for receiving pilot signals from base stations for which reception is possible but that have not been designated from radio link control unit 1006.
In accordance with requests of control unit 1001, radio link control unit 1006 designates to radio signal transceiver 1004 the base stations that are to transmit and receive signals.
FIG. 10 is a view for explaining a sequence that is executed between terminal 904 and base stations 902 and 903 when carrying out a soft hand-over.
Control unit 1001 of terminal 904 issues a request to signal measurement unit 1005 to measure the quality of pilot signals that are being received by radio signal transceiver 1004. Signal measurement unit 1005, having received the request to measure signal quality, measures the reception quality of all pilot signals that are being received by radio signal transceiver 1004 and reports the measurement results to control unit 1001 (Step 1201).
Control unit 1001, having received the measurement results that are reported from signal measurement unit 1005, specifies the base stations of base stations 902 and 903 that are transmitting signals having quality equal to or greater than a predetermined quality, and reports to message transceiver 1002 the generation of a message for reporting to RNC 901 the specified base stations and the reception quality of pilot signals from those base station. In this case, it is assumed that the reception quality of pilot signals that are received from base stations 902 and 903 exceeds the predetermined reception quality, and RNC 901 is notified that base stations 902 and 903 exceed the predetermined reception quality and is further notified of the reception quality of each base station.
Message processor 1002, having received the request from control unit 1001 to transmit a message, issues a request to message transceiver 1003 to transmit a measurement result report message to report the measurement results. Message transceiver 1003, having received the request from message processor 1002 to transmit a message, generates a measurement result report message and transmits the generated message by way of radio signal transceiver 1004 (Step 1202).
Message transceiver 303 of RNC 901, having received the report from terminal 904, reports the reception of the message to message processor 302; message processor 302 that receives the report recognizes that the message is a measurement result report message from terminal 904 and reports the reception of the measurement result report message and the reported measurement result to control unit 301.
Control unit 301 refers to the reported measurement result to verify whether the reported reception quality of pilot signals from the base station is equal to or greater than the predetermined quality (Step 1203). In this case, it is assumed that the reception quality of pilot signals that are received from base stations 902 and 903 is equal to or greater than the predetermined value.
Control unit 301 issues a request to message processor 302 to transmit a message to base stations 902 and 903 requesting the securing of radio resources required for radio communication with terminal 904. Message processor 302, having received the request, generates a resource request message and issues a request to message transceiver 303 to transmit the generated message. Message transceiver 303, having received the request, transmits the requested message to base stations 902 and 903 (Step 1204).
Upon receiving the resource request message, message transceivers 403 of each of base stations 902 and 903 report the reception of the message to message processors 402. Each message processor 402 that has received the report recognizes that the message is a resource request message and reports the reception of the resource request message to control unit 401.
Control unit 401 issues a request to radio signal transceiver 404 to secure radio resources, and radio signal transceiver 404 secures the radio resources (Step 1205). When radio resources have been secured, control unit 401 issues a request to message processor 402 to transmit a message to report to RNC 901 that radio resources have been secured.
Message processor 402 generates a resource securing completed message and issues a request to message transceiver 403 to transmit the generated message. Message transceiver 403 that receives the request transmits the resource securing completed message to RNC 901 (Step 1206).
Message transceiver 303 of RNC 901 that has received the resource securing completed message reports the reception of the message to message processor 302. Message processor 302 recognizes that the received message is a resource securing completed message and reports to control unit 301 that a resource securing completed message has been received from base stations 902 and 903.
Control unit 301, upon verifying that radio resources have been secured, issues a request to message processor 302 to transmit a message to change the settings of terminal 904 to use base stations 902 and 903 for communication. Message processor 302, having received the request, generates a setting change message and issues a request to message transceiver 303 to transmit the generated message. Message transceiver 303 transmits the setting change message to terminal 904 (Step 1207).
Message transmitter 1003 of terminal 904, upon receiving the setting change message by way of radio signal transceiver 1004, reports the reception of the message to message processor 1002. Message processor 1002 recognizes that the received message is a setting change message and reports to control unit 1001 the reception of the setting change message and the content of the change. In this case, it is assumed that the notification indicates changes such that both of base stations 902 and 903 are used simultaneously in the exchange of messages with RNC 901.
Control unit 1001, having received the notification, issues a request to radio link control unit 1006 to change the settings such that base stations 902 and 903 can both be used in the transmission and reception of data and voice signals. Radio link control unit 1006, having received the request, changes the settings of radio signal transceiver 1004 such that base stations 902 and 903 can both be used in the exchange of messages with RNC 901 (Step 1208). Upon completion of the settings, terminal 904 is able to use both of base stations 902 and 903 simultaneously to carry out communication with RNC 901.
However, in the RTD measurement method that uses GPS times that is established by the 3GPP standardization document TS 25.301, the problem exists that hardware that can receive GPS signals must be mounted in a base station.
In addition, although RTD measurement that uses LMUs such as prescribed in TS 25.301 can be considered, this approach also has the drawback that a plurality of LMUs must be newly installed.